Shift control system for vehicle automatic transmission

ABSTRACT

A shift control system for a vehicle automatic transmission including a transmission gear assembly and gear engaging means. The shift control system comprises both electrical and hydraulic controls and associated shift lever means, whereby the gear changing operation of the transmission is automatically controlled by the electrical control system according to the driving conditions thus providing a highly variable ratio transmission, while provision is made for the semiautomatic control of the transmission by means of the hydraulic circuit. The important features of both automatic and semiautomatic transmissions are thus embodied in one system.

United States Patent Ito et a1.

[ Mar. 7, 1972 [54] SHIFT CONTROL SYSTEM FOR 2,875,635 3/ 1959 Fleck et a1. ..74/860 I LE AUTOMATIC 3,165,940 1/1965 Grau ....74/859 X 3,335,830 8/1967 De Caste1et..... ....74/859 X TRANSMISSION 3,433,101 3/1969 Scholl et a1. ..74/866 [72] Inventors: Shin lto; Seitoku Kubo; Takakazu Mori,

all of Toyota, Japan Primary Examiner-Arthur T. McKeon I73] Aiisignce: Toyota .lidosha Kogyo Kabushlki Kaisha, Ammey CushmanDm-by &Cushman Toyota-shi, Japan [57] ABSTRACT [22] Fled: May 1970 A shift control system for a vehicle automatic transmission in- [21] A No; 35,787 cluding a transmission gear assembly and gear engaging means. The shift control system comprises both electrical and hydraulic controls and associated shift lever means, whereby [30] Forelgn Apphcamn Pnomy the gear changing operation of the transmission is automati- Oct. 18, 1969 Japan ..44/83412 coml'oned y the electrical Control system according to the driving conditions thus providing a highly variable ratio [52] U.S. Cl ..74/860, 74/866, 74/869 transmission, while provision is made for the semiautomatic 51 Im. (II ..B60k 21/08 control of the transmission y means of the hydraulic circuit. 58 Field or Search ..74/s59, 860, 866 The important features of both automatic and semiautomatic transmissions are thus embodied in one system. [5 6] Referenc 11 Claims, 31 Drawing Figures UNITED STATES PATENTS 2,771,788 11/1956 Frick et al ..74/860 W TRANSMISS/ON SH/FT CONTROL H YD/PAUL/C SYSTEM 5 954 7- PATENIEDMAR H972 3,646,835

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' sum IBM 18 INVENTOR'S 719/04 mm M021 BY 2 'DLJNH LATTORNEYS SHIFT CONTROL SYSTEM FOR VEHICLE AUTOMATIC TRANSMISSION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to transmission systems and it has a particular relation to a shift control system which combines electrical and hydraulic controls.

2. Description of the Prior Art In those automatic transmission for vehicles which have hitherto been used generally, all the complicated control operations including shift control were effected through hydraulic controls. Thus, with these hitherto available automatic transmission, it was not an easy matter to enable the shift control to perform more sophisticated functions, not to convey the drivers will to the shift control system. Another drawback was the difficulty of exactly controlling the shift points and thus, in order to effect variations in the setting of shift conditions (particularly, automatic shift conditions), an extremely complex and bulky system was needed.

SUMMARY OF THE INVENTION To solve these difficulties, it is the object of the present invention contemplates to electrically effect shift controls. At the same time a shift lever installed in the drivers compartment is provided with multiple series, such as two series of operating positions with each of said two series having its own shifting conditions. Other improvements in the electrical and hydraulic control systems are further effected.

According to an embodiment of the present invention, a shift lever is provided with an H-shaped shifting slotted gate which provides for the two series of the shift-lever positions, one of the two series giving the ranges for an automatic transmission which operates in the same manner as the conventional automatic transmissions, while the other series of positions being provided for the semiautomatic shift ranges so that shift control can be effected independently of the electrical system. This enables the driver to drive the vehicle at any desired speed ratio (that will suit the driving conditions) by moving the shift lever. Since these semiautomatic shift ranges are controllable independent of the electrical system, they are completely free from any effects due to the occurrence of a fault in the electrical system. Moreover, availability of both the full-automatic and semi-automatic operations also enables the driver to simultaneously either change gears or use the automatic transmission.

In another embodiment of the present invention, a shift lever is also adapted to work in an H-shaped two-slots shifting gate with one of the slots providing the proper automatic shift points to suit the normal driving conditions. In other words, there are provided an extended high gear range and a limited low gear range. This permits more economical driving and also quieter driving at lower engine speeds. In contrast to this, the other series of shift-lever positions provides an extended low gear range and a limited high gear range for sporty driving and driving in hilly country. In this manner, the present invention is capable of providing various settings of shift points thereby attaining a greater efficiency than is possible in the conventional automatic transmissions.

These objects are achieved by providing in an automatic transmission for vehicle including a transmission gear assembly and engaging means for effecting various gear changing engagements of said transmission gear assembly, a shift control system for a vehicle automatic transmission system comprising shifting actuation means for actuating said engaging means, signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means for acting upon on the signals produced by said signal generator means to determine shift condition (operating conditions) for actuating said shifting actuation means, shift condition modification means for changing said shift condition, and shift lever means having a plural series of gear shifting positions for actuating said shifting actuation means,

whereby when said shift lever is transferred from one of said plural series of gear shifting positions to the other series said shift condition modification means is actuated to change said established shift condition.

Another object of the present invention is to provide a shift control system for a vehicle automatic transmission including a transmission gear assembly and engaging means for effecting various gear changing engagements of said transmission gear arrangement, said shift control system comprising shifting actuation means for actuating said engaging means, signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means for acting upon the signals produced by said signal generator means to determine shift condition (operating conditions) for actuating said shifting actuation means, a first electrical circuit for receiving the output signal from said shift condition to effect an automatic shifting action, a second electrical circuit adapted to cut off the output signal from said shift condition thus effecting a semiautomatic shifting action, and shift lever means having two series of gear shifting positions for actuating said shifting actuation means, wherein one of said two series of gear shifting position is associated with said first electrical circuit, and the other series is associated with said second electrical circuit, whereby selection of the gear shifting columns of said shift lever means changes the shift condition for an automatic shifting action or semiautomatic shifting action.

A still further object of the present invention is to provide a shift control system for a vehicle automatic transmission including a transmission gear assembly and engaging means for effecting various gear shifting engagements of said transmission gear assembly, said shift control system comprising shifting actuation means for actuating said engaging means, signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means for operating on the signals produced by said signal generator means to determine the shift conditions (operating conditions) for actuating said shifting actuation means, a shift point modification circuit, first shift point establishing means for applying the signal from said shift point modification circuit to said shift condition establishing operational circuit to establish the shift point, second shift point establishing means for cutting off the signal from said shift point modification circuit to said shift condition establishing operational circuit to establish the shift point, and shift lever means having two series of gear shifting positions for actuating said shifting actuation means, wherein one of said two series of gear shifting positions is associated with said first shift point establishing means, and the other series is associated with said second shift point establishing means, whereby selection of the gear shifting columns of said shift lever means changes the shift point for the automatic shifting action.

Other objects of the present invention will be apparent from the following descriptions of embodiments of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an automatic transmission incorporating the shift control system of the present invention.

FIG. 2 is a schematic view showing by way of an example the principle of a transmission gear assembly used with the system of the present invention.

FIG. 3 is a partial sectional view taken on the line A-A of FIG. 2, showing in detail the relationships between an idler gear not shown in FIG. 2 and gears associated therewith.

FIGS. 4 through 8 are hydraulic diagrams showing the conditions of a hydraulic actuation circuit incorporated in the system of the present invention, the conditions corresponding to various operating positions, FIG. 4 showing the conditions in the N position, FIG. 5 in D, third speed position, FIG. 6 in D, second speed position, FIG. 7 in L first speed position, and FIG. 8 L second speed position. 

1. In a shift control system for a vehicle automatic transmission which includes a transmission gear assembly and engaging means for effecting gear changing engagements of said transmission gear assembly, and a shifting means for operating said engaging means, the improvement comprising signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means for acting upon the signals from said signal generator means to establish a shift condition for actuating said shifting means, shift condition modification means for varying said shift condition, and a shift lever having plural series of gear shifting positions for actuating said shifting means, and means associated with said shift lever for operating said shift modification means to vary said shift condition when said shift lever is transferred from one to the other of said plural series of gear shifting positions.
 2. In a shift control system for a vehicle transmission which includes a transmission gear assembly and engaging means for effecting gear changing engagments of said transmission gear assembly, and shifting means for operating said engaging means, the improvement comprising signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means to determine a shift condition for actuating said shifting means, a first electrical circuit for receiving the output signal from said shift condition-establishing circuit to effect an automatic shifting action, a switching circuit adapted to cut off the output signal from said shift condition establishing circuit to effect a semiautomatic shifting action, and shift lever means having two series of gear shifting positions for actuating said shifting means, wherein one of said two series of gear shifting positions is associated with said first electrical circuit and the other of said two series is associated with said switching circuit, whereby selection of the gear shifting columns of said, shift lever means changes the shift condition for an automatic shifting action or semiautomatic shifting action.
 3. In a shift control system for a vehicle automatic transmission which includes a transmission gear assembly and engaging means for effecting gear shifting engagements of said transmission gear assembly, and shifting means for operating said engaging means, the improvement comprising signal generator means for producing electrical signals representative of the driving conditions of the vehicle, circuit means for operating on the signals from said signal generator means to establish a shift condition for actuating said shifting actuation means, a shift point modification circuit, switching means for selectively connecting said shift point modification circuit to said establishing circuit to modify the shift point when said switching means is in a closed position and shift lever means having two series of gear shifting positions for actuating said shifting actuation means, wherein one of said two series of gear shifting positions opens said switching, and the other series closes said switching means, whereby selection of the gear shifting columns of said shift lever changes the shift point for the automatic transmission.
 4. In a shift control system for a vehicle transmission which includes a transmission gear assembly, engaging means for effecting gear shifting engagement of said transmission gear assembly, and shifting means for operating said engaging means, the improvement comprising, a shift lever having plural series of gear shifting positions for actuating said shifting means, signal generator means for producing electrical signals representative of the operating conditions of the vehicle, a circuit connected to the output of said signal generator means for acting upon the output signals therefrom to establish a shift condition and an electrical operator connected to the output of said establishing circuit for actuating said shifting means in conjunction with said shift lever, a shift condition modification circuit connected to said establishing circuit for varying said shift conditions, and means associated with said shift lever for operating said shift condition modification circuit when said shift lever is in one of said plural series.
 5. The shift control system of claim 4 wherein said signal generating means comprises a toothed disc of magnetic material securely mounted coaxially on the output shaft of said vehicle transmission and a coil located adjacent to the outer periphery of said toothed disc the axis of said coil being located on a line radial to said disc whereby a voltage having a frequency proportional to the rotational speed of said output shaft is induced in said coil.
 6. The shift control system of claim 5 further including a digital to analog converter electrically connected between said coil and said establishing circuit.
 7. The shift control system of claim 4 wherein said signal generating means comprises a movable contact mechanically connected with the carBuretor throttle of said vehicle, a plurality of fixed contacts arranged to engage with said movable contact, each of said fixed contacts being connected through a separate resistance to a source of electrical power, and a voltage tap line connected in common between said resistances and said power source wherein the movement of said carburetor throttle causes said movable contact to engage a varying number of fixed contacts and thus to vary the output voltage on said voltage tap line proportional to the setting of said carburetor throttle.
 8. The shift control system of claim 4 wherein said signal generating means comprises a toothed disc of magnetic material securely mounted coaxially on the output shaft of said vehicle transmission and a coil located adjacent to the outer periphery of said toothed disc the axis of said coil being located on a line radial to said disc whereby a voltage having a frequency proportional to the rotational speed of said output shaft is induced in said coil, and a movable contact mechanically connected with the carburetor throttle of said vehicle, a plurality of fixed contacts arranged to engage with said movable contact each of said fixed contacts connected through a separate resistance to a source of electrical power and a voltage line connected in common between said resistances and said power source wherein the movement of the carburetor throttle causes said movable contact to engage a varying number of said contact and thus to vary the output voltage of said voltage tap line proportional to the carburetor throttle setting.
 9. The shift control system of claim 4 wherein said shifting means comprises a source of pressurized liquid and a hydraulic system having at least one valve for controlling the flow of liquid within said hydraulic system and at least one hydraulic operator in liquid connection with said hydraulic system and in mechanical connection with said engaging means for operating said engaging means.
 10. The shift control system of claim 9 wherein said engaging means comprises at least one clutch and said hydraulic operator comprises a servo chamber mechanically adapted to cause the engagement of said clutch.
 11. The shift control system of claim 9 wherein said engaging means comprises at least one brake band and said hydraulic operator comprises a servo chamber mechanically adapted to cause the engagement of said brake band.
 12. The shift control system of claim 4 wherein said signal generating means produces two signals and said establishing circuit comprises a comparator having first and second input leads and an output lead, one of said two signals being applied to said first input lead and the other of said two signals being applied to said first input lead, said comparator producing an output on said output lead only when said first signal exceeds said second signal.
 13. The shift control system of claim 12 further including a feedback circuit connected between said output lead of said comparator and said first input lead thereof for adding a portion of the output signal produced by said comparator to the input signal at said first input lead whereby signals on said output lead are stabilized.
 14. The shift control system of claim 12 wherein said shift modification means comprises a second comparator which is electrically identical to the first comparator and has electrically identical input and output leads but differs from said first comparator in that said second signal is applied to the first input lead of said second comparator and said first signal is applied to the second input lead of said second comparator whereby said second comparator produces an output only when second signal exceeds said first signal, and an electrical gate to which gate the output leads of said first and second comparators are connected as inputs and from which gate an output lead extends which is connected to said electrical operator.
 15. The shift control system of claim 14 wherein said means associated with said shift Lever for operating said shift modification means comprises a third input lead to said gate which operates said gate to connect the output of either said first or said second comparator to said electric operator.
 16. The shift control system of claim 15 further including a source of electric power and a switch associated with said shift lever both connected on said third input lead whereby said source of electrical power can be connected to or disconnected from said third input lead.
 17. The shift control system of claim 12 wherein said shift condition modification circuit comprises a voltage divider means for presenting one of said signals to said second input lead and switch means for changing the voltage divider proportion whereby the input to said second input lead is varied. 